Handbook for Irrigation of Wine Grapes in South Africa

Figure 8.2 Figure 8.2

A

B

FIGURE 8.2. Where (A) compaction limits root development in the work row, (B) the soil can be loosened between the wheel tracks by means of a wiggle plough to encourage root development.

FIGURE 8.3. An example of where root pruning stimulated the formation of numerous new grapevine roots.

8.3

INDIRECT ESTIMATION OF EVAPOTRANSPIRATION

This approach is used world-wide to estimate the irrigation requirements of most agricultural crops, including vineyards. The approach is based on the relationship between vineyard ET and a reference evaporation or evapotranspiration. Both ET and the references are usually in millimeters per day (mm/d). When the reference

238 CHAPTER 8 – PRACTICAL IRRIGATION SCHEDULING